DNS Change Scenario Help

Website, Application, Performance DNS & Network
1

We are moving are web servers from a datacenter to Azure. The DNS provider will stay the same, but we will be using a CNAME record to point to Cloudflare so we can take advantage of the WAF capability only. The Authoritative DNS will remain the same.

My question is about the A record.

Current set up:

A record - example.com - IP of virtual server at datacenter (this will be offline a few days later)
CNAME - www.example.com - Azure traffic manager DNS name

Question:

We will ask to have the CNAME record to point to our Cloudflare account, which will then use Cloudflare to point to the Azure traffic manager. No problem.

But what about the A record? We will need to change the IP the A record points to. The night we move to Azure, we want to point the A record to a new IP in Azure. While DNS updates, will the CNAME look ups fail since it is being changes from the old IP at the data center to the new IP in Azure.

2

You are at least on a business plan on Cloudflare, right?

3

Yes have a business account.

4

In this case https://support.cloudflare.com/hc/en-us/articles/360020615111-Configuring-a-CNAME-setup should cover your questions.

5

We have the set up ready and should work perfectly.

But what happens when we update the A record a few days later, during the migration to Azure, and people go to www.example.com, the CNAME. Will the CNAME still work if the A record is in the middle of being updated from x.x.x.1 to x.x.x.2 ?

6

Where does the Cloudflare CNAME come in though? As far as I understand the www record is a CNAME pointing to Microsoft, not Cloudflare. Right?

7

The CNAME will point to Cloudflare. We then set up a CNAME in Cloudflare to point to Microsoft. We walked through this with Cloudflare Support and everything is set up form that end.

But the A record itself still points to an IP that is the web server we are moving from. We are just wondering if making any changes to the A record will impact CNAME record lookups.

I appreciate your help with this.

8

All right, the CNAME does not point to the A record, right? In that case these two should be independent.

If the machine with the IP address where the A record points to, becomes unavailable, so will the A record. Well, not unavailable but the connection wont work. However that should not affect the CNAME.

Did I misunderstand anything in your question?

9

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